In general, a laundry treating apparatus having a drying function such as a washer or dryer is a device for putting the laundry in a state that washing is completed and the dehydration process is finished into the drum, and supplying hot air into the drum to evaporate the moisture of the laundry and dry the laundry.
For example, a dryer may include a drum rotatably provided within the body to put the laundry thereinto, a drive motor configured to drive the drum, a blower fan configured to blow air into the drum, and a heating device configured to heat the air flowing into the drum. Furthermore, the heating device may use electrical resistance heat at high temperature generated using an electrical resistance or the heat of combustion generated by burning gas.
Air coming out of the drum may contain the moisture of the laundry within the drum, thus becoming air under a medium temperature and humidity condition. Here, a dryer can be classified according to a method of treating the medium temperature and humid air, and can be divided into 1) a condensation type (circulation type) dryer for cooling air below its dew-point temperature through the condenser while circulating the medium temperature and humid air without being exhausted to the outside to condensate moisture contained in the medium temperature and humid air, and 2) an exhaustion type dryer for allowing the medium temperature and humid air to be directly exhausted and wasted to the outside.
In case of the condensation type dryer, in order to condensate air exhausted from the drum, the air should be subject to the process of cooling below the dew-point temperature and heated through the heating device prior to being supplied to the drum. Here, a loss of heat energy contained in the air may be generated while being cooled during the condensation process, and an additional heater or the like may be needed to heat the air to a temperature required for drying.
In case of the exhaustion type dryer, it may be required to exhaust the medium temperature and humid air to the outside and inhale ambient air to heat the air to a temperature level required for drying through a heating device. In particular, high temperature air being exhausted to the outside contains heat energy transferred by the heating device; because the air is exhausted and wasted to the outside, heat efficiency be reduced.
Accordingly, in recent years, laundry treating apparatuses for collecting energy required to generate hot air and energy being exhausted to the outside without being used have been introduced to increase energy efficiency, and a laundry treating apparatus having a heat pump system has been introduced as an example of such laundry treating apparatus. The heat pump system may include two heat exchangers, a compressor and an expansion apparatus, and energy contained in the exhausted hot air is recovered and reused in heating up air being supplied to the drum, thereby increasing energy efficiency.
Specifically, in the heat pump system, an evaporator is provided at the exhaust side, and a condenser at an inlet side of the drum, and thus thermal energy is transferred to refrigerant through the evaporator and then thermal energy contained in the refrigerant is transferred to air flowing into the drum through the condenser, thereby generating hot air using waste energy. Here, a heater for reheating air that has been heated up while passing through the evaporator may be additionally provided therein.
However, the heat pump system should be additionally provided with a compressor, an expansion apparatus, and the like in addition to the two heat exchangers. As an alternative of the heat pump system, there exists also an example of using a heat pipe. The heat pipe can transfer heat from the high temperature side to the low temperature side while sealed refrigerant repeats evaporation and condensation with no additional power source.